The antibotic nogalamycin, and a process for its preparation, are described in U.S. Pat. No. 3,183,157. The structure of nogalamycin can be shown as follows: ##STR1##
Antibotics nogalarol and nogalarene, produced by acid hydrolysis of nogalamycin, and O-methylnogalarol, produced by acidic methanolysis of nogalamycin or nogalarol, are disclosed in U.S. Pat. No. 3,501,569.
Nogalamycinic acid is prepared by chemical modification of nogalycimin. THe structure of nogalamycinic acid is as follows: ##STR2##
Nogalamycinic acid can be converted to nogamycin by contacting it with dimethylformamide (see U.S. Pat. No. 4,064,340). Nogamycin has the following structural formula: ##STR3##
It is now found that the nogamycin prepared in the process of the above citation does not have the same structural formula as the nogamycin produced in the process of the instant invention.
U.S. Pat. No. 4,086,245 and U.S. application Ser. No. 924,975 concerns 7-1-alkylnogarols and their preparation from nogamycin.
Acid alcoholysis of nogamycins is the process used in the above preparations of 7-0-alkylnogarols having the following formulas: ##STR4## wherein R is an alkyl group of from 1 to 4 carbon atoms, inclusive;
Additional prior art includes disclosure by Tong et al.; in Abstracts of Papers, 175th ACS meeting. Medicinal Division, paper 48, for a process which treats dauno:oethanethiol in trifluoroacetic acid mycinone with 2-aminoethanethiol in trifluoroacetic acid solution to obtain two diastereomers of a 7-(2-aminoethylthio) derivative.
Demonstrated advantageous biological use for the 7-0-alkylnogarols are included in U.S. Patent 4,086,245 and copending U.S. Ser. No. 924,975. Nogamycin itself has a demonstrated advantageous use in U.S. Pat. No. 4,064,340.